Tabular rack assembly

ABSTRACT

A typewriter tabular rack is provided with tab stops held in frictional engagement with a rack element in either set or reset positions by, in one embodiment, the compressional stresses set up in a resilient stop mounting strip. The strip also serves to maintain the tab stops properly spaced and as a fulcrum when the stops are moved between set and reset positions. In another embodiment flexure stresses set up in the tab stops when mounted on a rack element serve to provide the force urging the tab stops into frictional engagement with a rack element.

United States Patent [72] Inventor RalphLParlrer Rockvllle,Coiu|. [21] AppLNo. 745,295 [22] Filed July16,1968 [45] Patented June 8,1971 [73] Assignee Litton Business Systems, Inc.

New York, N.Y.

(54] TABULAR RACK ASSEMBLY 2 Claims, 4 Drawing Figs.

[52] U.S.C1. 197/179, 197/70 [51] lnt.C1 ..B41j21/02, B4lj21/04 [50] FieldofSeareh ..197/179,70

[56] References Cited UNITED STATES PATENTS 1,066,053 7/1913 Roberts 197/179 1,247,084 11/1917 Corcoran.... 197/179 2,146,821 2/1939 Helmond 197/179 2,265,483 12/1941 Hill 197/179 2,547,443 4/1951 Crumrine 197/179 2,852,120 9/1958 Braun et al. 197/70 3,283,872 1 H1966 Prechette 197/1 79X 3,294,213 12/1966 .10nss0n..... 197/179 3,333,669 8/1967 Schaefer 197/179 FOREIGN PATENTS 660,043 l/1964 Italy 197/179 745,564 12/1943 Germany 197/70 Primary Examiner-Robert E. Pulfrey Assistant Examiner-Stephen C. Pellegrino AnorneysJoseph R. Spalla and Cornelius P. Quinn ABSTRACT: A typewriter tabular rack is provided with tab stops held in frictional engagement with a rack element in either set or reset positions by, in one embodiment, the compressional stresses set up in a resilient stop mounting strip. The strip also serves to maintain the tab stops properly spaced and as a fulcrum when the stops are moved between set and reset positions. In another embodiment flexure stresses set up in the tab stops when mounted on a rack element serve to provide the force urging the tab stops into frictional engagement with a rack element.

PATENTED JUN am INVENTOR RALPH L. PARKER BY fiJ/%.

ATTORNEY TABULAR RACK ASSEMBLY BACKGROUND OF THE INVENTION This invention relates to tabular rack assemblies for typewriters or like machines; more particularly it relates to tabular rack assemblies characterized by tab stops which non detentably frictionally engage a rack element; and specifically the invention relates to a tabular rack wherein the forces resulting in the frictional engagement of the tab stop with a rack element are provided by stresses set up in a resilient tab stop fulcrum when the rack is assembled.

Nondetenting tab stop assemblies provided in the prior art which rely on friction to hold tab stops positioned in set and reset or clear status are not altogether satisfactory in that the structures required to provide the friction necessary to reliably maintain tab stops positioned are subject to wear, are costly to fabricate and difficult to assemble. Tabular racks having viscous materials to provide resistance to unwanted stop movement are in use. These racks are characterized by tab stops having relatively large surface areas in contact with the viscous material to provide sufficient resistance and the viscous materials such as grease are subject to loss and contamination.

In accordance with several embodiments of the invention a resilient tab stop anchoring strip is trapped and compressed between a contoured edge of a tab stopand a surface of the tab rack assembly whereby the compressional force urges a peripheral edge of the tab stop opposite the contoured edge into frictional engagement with another surface of the tab rack assembly. In one embodiment a generally C-shaped tab stop encircles, in turn, a support rod, one side of an elongated channel-shaped slotted guide bar and the resilient strip; the compressional force set up in the strip serves to urge the tab stop into frictional engagement with the support rod. In another embodiment a channel-shaped slotted guide barencloses the tab stops and a rubber or resilient strip and the compressional force set up in the rubber serves to urge the tab stop into frictional engagement with an opposite guide bar surface. In still another embodiment which dispenses with the rubber strip, flexure forces set up incident to mounting a C-shaped tab stop about a support rod and one leg of a channel-shaped guide bar by anchoring the stop to the bar and forcing it about the rod, urge the tab stop into frictional engagement with the support rod. In all embodiments extensions of the tab stops project through slots in the guide bar.

A feature of the embodiments utilizing rubber strip mounting resides in the fact that deformation of the rubber between adjacent tab stops acts to maintain the tab stops properly spaced.

An object of the invention is to provide a low-cost nondetenting type tab rack assembly.

Another object of the invention is in the provision of a nondetenting tab rack assembly wherein tab stops are urged into frictional engagement against a guide bar by the compressional forces set up in a resilient strip incident to mounting the tab stops in the assembly.

Still another object of the invention is in the provision of a rubber tab stop anchoring strip to provide the force necessary to maintain tab stops positioned through friction and wherein the flow of rubber between tab stops provides the necessary support to maintain the tab stops aligned.

A further object of the invention is to provide a tab rack assembly wherein all set stops may be cleared solely by manipulation of the tab rack assembly.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes FIG. 2 is a cross-sectional view of another embodiment similar to that ofFIG. 1;

FIG. 3 is a partial perspective view ofa tab rack assembly in accordance with a further embodiment ofthe invention; and

FIG. 4 is a partial perspective view of still another embodiment of the tab rack assembly.

Referring now to the drawings wherein like reference numerals designate like or corresponding elements throughout the several views there is shown in FIG. 1 a preferred embodiment ofa tab rack assembly generally designated by reference numeral 10 which mounts an array of tab stops ll positionable to set 118 and reset 11R or clear positions. Set and reset abutments designated S and R are associated with the tab rack assembly as is a tab blade or sensing element 12. The tab rack assembly 10 may be utilized with conventional typewriters having a carriage movable relative to a fixed printing point, in which case the assembly 10 would be mounted on the carriage frame, and the abutments R and S and blade 12 on the machine frame with tabular movement of the assembly 10 in the direction of arrow 13, or it may be utilized with machines wherein a single printing element is mounted on a carriage, in which case the tab rack assembly 10 will be rockably mounted in the typewriter machine frame and the abutments R and S and tab blade 12 on the printing element carriage whose tab movement would be in the direction of arrow 14. Thus the reference character F represents either a machine or a carriage frame In both types of machine a tabulation function releases the carriage from its escapement and places the normally retracted tab blade 12 in position to intercept or be intercepted by a set tab stop 185. A latch mechanism maintains this status until a set stop 185 and tab blade 12 encounter one another, tripping the latch and allowing reengagement of the carriage with its escapement. In conventional machines the tab stops 11S absorb carriage energy and arrest the carriage. In single element machines, the reengagement of the carriage escapement arrests carriage motion.

More particularly the rack assembly 10 of FIG 1 comprises a transverse support rod 15 whose ends are suitably journaled in side frames F for rocking movement in either set or reset directions from a neutral normal operative position in response to manipulation of a tab set and clear key, operative on a crank arm (not shown) secured to one end of the support rod 15.

The tab rack assembly 10 also comprises a transverse guide bar generally designated by reference numeral 16 and which is generally C- or channel-shaped in cross section having from left to right as viewed in FIG. 1 a circularly shaped upwardly directed section or wall 16a to accommodate the circular sup port rod 15, a downwardly and forwardly extending section 16b and a vertically extending section provided with slots 17 at carriage position intervals to accommodate tab stop extensions 18 projecting through slots 17. An elongated resilient rubber strip 19 is positioned against the outer periphery of the circular section 16a, and, with the support 15 rod, sandwiches the circular guide bar section 16a. The strip 19 serves to anchor and fulcrum the tab stops 11 and to urge them into frictional engagement with the support rod 15. More particularly each tab stop 11 in FIG. 1 is generally rectangular and is formed with an oblong generally C-shaped cutout 20 opening on the lower edge. The rear and forward edges 21 and '22 defining the cutout 20 are arcuately shaped and spaced a distance less than the diameter of the support 15 rod plus the thickness of guide bar 16 and rubber strip 19. The forward edge 22 has a retaining projection 23 so that when the rear edge 21 is placed against the rubber strip 19, and the strip 19 is compressed, the forward edge 22 may be forced about and encircle the support rod 15 with the compressional force set up in the rubber strip 19, urging edge 22 into frictional engagement-with rod 15. The friction between the forward edge 22 of the cutout 20 and the periphery of the support rod 15 serves to hold the stops 11 positioned in either set or reset position the. said edge 22, where the rod 15 is facing it, being substantially concentric with the pivot axis which for the stops I1 is afforded at the wall section 16a As viewed in FIG. 1 when the stops 11 are so mounted the rubber deforms and flows in the spaces as at 24 between the rear ends of the tab stops 11 and thus acts as a spacer element. It will be seen that the wall section 160 and the rod 15 afford an elongate means having oppositely facing faces, one facing toward the slotted wall section 160 and the other facing away from it.

With the stops 11 so mounted and in assumed clear or reset positions, movement of the support rod 15 in a counterclockwise or set direction, indicated by arrow 25, frictionally carries the guide bar 16 and all of the stops II counterclockwise except the one in line with abutment S which will be held against movement by the abutment S and thus will be moved relative to the guide bar 16 to a set position 118 as shown when the rod 15 is returned to neutral. Thus the stopsetting movement takes place against the sliding friction between the rod 15 and the one stop 11 being set. To clear a stop 11 at a particular position the rod 15 is moved clockwise or in a reset direction, indicated by arrow 26 from and back to neutral. In doing so, the guide bar 16 and all set stops 115, as well as reset stops 11R, move clockwise except the set stop 11S opposite reset abutment R which arrests movement of that set stop 11S and moves it relatively to the guide bar 16 to clear position.

As often happens, it is necessary to clear all set stops 118 when work with a different format is to be done. In the prior art it has been necessary to effect relative movement between carriage and a camming abutment, usually the reset abutment. As viewed in FIG. I however, all of the tab stops US in a set position may be simultaneously cleared by rocking rod 15 from neutral to clear and back again. Thus to clear all set stops 118, one first operates a male detent 27 upwardly into engagement with a female detent 28 secured to the underside of the guide bar 16 thus to restrain movement of the guide bar 16. Then the support rod 15 may be moved clockwise to clear position. As the guide bar 16 is now restrained, all reset stops 11R will be carried downward or clockwise into alignment with previously set stops 118 which, being restrained by the bottom 29 of the guide slots 17 in the now stationary guide bar 16, will be moved relative thereto. Thus all stops 11 will be aligned. Return of the support rod 15 to neutral position will then carry all of the now-aligned stops relative to the stillrestrained guide bar 16 to reset position. A separate "all clear" key which serially engages the detent 27 and rocks support rod 15 clockwise can be provided, on alternatively a detent-engaging key operated in conjunction with the normal clear key can be employed.

The embodiment shown in FIG. 2 employs a guide bar support 16 and rod 15 configuration identical to that of FIG. I. The tab stops II in this embodiment however differ in that the rear edge of the cutout formed in each tab stop 11 is formed with a forwardly directed tooth having a sharp point 32 and the distance between point 32 and the forward edge 22' of the cutout 20 is less than the diameter of the support rod 15 plus the guide bar thickness at the section 16a. When the point 32 of the tab stop 11 is held in point contact against the guide bar section 16a, as indicated in FIG. 2 and the stop 11 is rocked thereabout in contact with the support rod 15, the flexure stresses prevalent in the tab stop 11 not only anchor the tooth point 32 but supply the gripping frictional force between tab stop surface 22 and support rod periphery. This embodiment is functionally the same as that of FIG. I but dispenses with a resilient anchor strip through subjection of the stop 11' to distorting stress. The point 32 on the stop 11' in FIG. 2 is schematically shown as having established its own anchorage in the curved wall section 161 With reference to FIG. 3 there is shown another tab rack as sembly generally designated by reference numeral 33 characterized by a modified Cshaped slotted guide bar generally designated by reference numeral 34, such guide bar having a vertically disposed rear section 35, an arcuate forward section 36 provided with slots 37 and a horizontal lower section or wall 38 joining the rear section 35 and forward section 36. The tab stops 39 in this embodiment are formed with a contoured rear edge 41 and with a body that increases in width in the forward direction. The forward edge 42 is arcuate and complimentary to the inner surface of the guide bar arcuate section 36 and tab stop extensions 43 project through the slots 37 in the arcuate section 36. The rear edges 41 are curved and anchored in a rubber strip 44 adjacent the inner side of the rear section 35 and the compressional force set up in the rubber strip 44 urges the forward edge 42 of the tab stops 39 into frictional engagement with the inner surface of the arcuate section 36. Again rubber deformation maintains the rear ends M of the stops 39 spaced and aligned. End stops 45 are formed with tabs 46 complimentary to notches 47 cut in the ends of the guide bar 34 and stub shafts 48, secured as by welding to the end stops 45, are journaled in Frame F. Rotation of one of the stub shafts 48 by a crank controlled by a tab set clear key will rock the guide bar 34 clockwise or counterclockwise, as the case may be, which will frictionally carry along the array of stops 39, whether set or unset, with the exception of the stop 11 which is located aligned with the set and reset abutments S and R, which, as hereinbefore noted, will block stop movement and thereby will force pivotal movement relative to the guide bar 34. Thus a tab stop 39 located at the abutment position will be set or reset. In this modification all stops 39 in set position may be cleared by calling for relative movement between abutments R and S and tab rack 33 assembly in a carriage return direction (opposite arrows 13 or 14 as the case may be) while holding the clear key depressed to rock the tab rack 33 assembly clockwise whereby set stops 398 will be cammed upwardly by the reset abutment R as they pass relative to the abutment R.

With reference to FIG. 4 which shows another embodiment there is provided a channel-shaped guide bar generally designated by reference numeral 50 which has an arcuate forwardly facing wall or section 51 provided with guide slots 52 and upper and lower rearwardly extending walls or sections 53 and 54.

Except for end stops 55 each tab stop 49 in the array of FIG. 4 has a central circular opening 56 through which a support rod 57 freely extends. The rear edge 58 of each stop 49 is circular and the forward edge 59 is arcuately shaped complimentary to the inner surface of the forward section of the guide bar 50 and has an extension or tongue 61 which projects from the forward edge through slot 52 in the guide bar 50. The rear ends of the stops 49 are frictionally anchored in a rubber strip 62 held by a backing plate 63 which is held to the assembly by slitting and crimping over tabs 64 so formed on the guide bar 50. End stops 55 are keyed to and are rotated with the support rod 57. They are further shaped to conform to the inner periphery of the guide bar 50 and thus serve to rotate the guide bar 50. The FIG. 4 modification is functionally the same as the FIG. 3 embodiment.

Assembly of the FIG. 3 modification may be accomplished by first inserting the tab stop extension 43 through the slots 37 in the guide bar 34, the latter resting with its arcuate section 36 in a slotted fixture designed to locate the stop extensions 43 projecting through and hold them aligned. After positioning the rubber strip 44, the rear wall section 35 of the guide bar 34 is then bent forwardly to the final assembly position shown trapping strip 44 and stops 39.

Assembly of the FIG. 4 modification may be accomplished in a substantially similar fashion.

It should be understood that the foregoing disclosure relates to only a preferred embodiment of the invention and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purposes of the disclosure which do not constitute departures from the spirit and scope of the invention.

The invention I claim is:

1. In combination with a stop-supporting structure comprising,

an elongate wall having a row of stop-guiding slots extending therethrough,

and an elongate means being parallel to said wall and affording at a distance from said wall a first elongate face facing away therefrom and affording between said wall and said first face a second elongate face facing toward said wall,

a series of stops having generally C-shaped cutouts facilitating their association with the stop-supporting structure so that said elongate means is situated in said cutouts, said stops having stop ends extending through said guiding slots and having each a sharp point in its cutout by which it has pivotal anchorage contact with said first face,

each stop having in its C-shaped cutout a face concentric to its pivotal anchorage contact with said first face, the relative locations of the faces on said elongate means being such as to strain the stops in the region of said cutouts to render the stops movable between set and unset positions against frictional resistance.

2. A stop-supporting rack assembly comprising,

a stop-supporting structure having an elongate first wall and having an elongate second wall being transversely spaced from said first wall and extending parallel thereto,

said first wall having a row of slots extending transversely therethrough in the direction in which said walls are spaced,

a series of stops having each between said walls a main body portion which extends transversely of such walls and having each a stop tongue extending through one of said slots in said first wall to project outwardly therefrom,

means including said second wall to associate the said stops individually for frictionally opposed pivotal setting movements about an axis location remote to said first wall and reacting against said second wall,

said first wall being curved transversely of its length about an axis situated between said two walls,

the slots in said first wall being of lengths to permit setting movements of said stops and the tongues about said axis location, each of said stops having an edge in contact with the curved wall beyond each of the opposite ends of the related slot,

and a pivotal anchorage end on each stop facing toward said second wall out of contact with it,

said means comprising a resiliently compressible member situated between said second wall and the anchorage ends of said stops to urge said stop edges thereon against said curved surface beyond the opposite ends of the slots, whereby said stops are frictionally held in the positions to which they are moved. 

1. In combination with a stop-supporting structure comprising, an elongate wall having a row of stop-guiding slots extending therethrough, and an elongate means being parallel to said wall and affording at a distance from said wall a first elongate face facing away therefrom and affording between said wall and said first face a second elongate face facing toward said wall, a series of stops having generally C-shaped cutouts facilitating their association with the stop-supporting structure so that said elongate means is situated in said cutouts, said stops having stop ends extending through said guiding slots and having each a sharp point in its cutout by which it has pivotal anchorage contact with said first face, each stop having in its C-shaped cutout a face concentric to its pivotal anchorage contact with said first face, the relative locations of the faces on said elongate means being such as to strain the stops in the region of said cutouts to render the stops movable between set and unset positions against frictional resistance.
 2. A stop-supporting rack assembly comprising, a stop-supporting structure having an elongate first wall and having an elongate second wall being transversely spaced from said first wall and extending parallel thereto, said first wall having a row of slots extending transversely therethrough in the direction in which said walls are spaced, a series of stops having each between said walls a main body portion which extends transversely of such walls and having each a stop tongue extending through one of said slots in said first wall to project outwardly therefrom, means including said second wall to associate the said stops individually for frictionally opposed pivotal setting movements about an axis location remote To said first wall and reacting against said second wall, said first wall being curved transversely of its length about an axis situated between said two walls, the slots in said first wall being of lengths to permit setting movements of said stops and the tongues about said axis location, each of said stops having an edge in contact with the curved wall beyond each of the opposite ends of the related slot, and a pivotal anchorage end on each stop facing toward said second wall out of contact with it, said means comprising a resiliently compressible member situated between said second wall and the anchorage ends of said stops to urge said stop edges thereon against said curved surface beyond the opposite ends of the slots, whereby said stops are frictionally held in the positions to which they are moved. 